Without limiting the scope of the present invention, its background will be described in relation to subterranean well operations performed from floating platforms, as an example.
Drilling rigs supported by floating drill ships or floating platforms are often used for offshore well development. These rigs present a problem for the rig operators in that ocean waves and tidal forces cause the drilling rig to rise and fall with respect to the sea floor and the subterranean well. This vertical motion must be either controlled or compensated while operating the well. Without compensation, such vertical movement may transmit undesirable axial loads on the rigid tubular strings that extended downwardly from the drilling rig. This problem becomes particularly acute in well operations involving fixed bottom hole assemblies, such as packers.
For example, once a lower completion has been installed in a casing string or open hole location, it is common to stab the lower end of the upper completion, run into the well on a tubing string, into the packer at the top of the lower completion assembly. Typically, the connection operation requires that the tubing string apply a predetermined amount of axial and/or rotational force against the packer. Once connected, any vertical movement from the ship or platform will create undesirable downward and upward forces on the packer or may cause premature failure of components.
One way to reduce the undesirable downward and upward forces is to install a travel joint in the tubing string which allows for telescopic extension and contraction of the tubing string. Typically, the travel joint is run downhole in a locked position, then unlocked once the tubing string is connected to the packer. It has been found, however, that in certain wellbores such as highly deviated wellbores, a travel joint may prematurely unlock. For example, in deep water offshore drilling operations, it is routine to drill a number of wells from a single platform. Each well is directionally drilled to a target location in a zone of interest, which may be a lengthy horizontal distance from the platform. Therefore, significant force is sometimes required to push the tubing string as it slides along the inner wall of the casing string. This force may unlock the travel joint prior to stinging into the packer. Once unlocked, it is virtually impossible to sting into the packer without relocking the travel joint, which may require an additional trip out of the well to redress the travel joint.
In addition, it has been found, that there may be uncertainty relating to whether a premature unlocking has taken place. With certain prior art type travel joints, no accurate means is available for gauging whether the travel joint has become unlocked. Often, the first indication that the travel joint is in the unlocked position manifests itself when the tubing string will not sting into the packer. At that point, the entire tubing string may need to be removed from the wellbore, reset or redressed, and then run in again with the hope that the travel joint will not become unlocked.
Accordingly, a need has arisen for a travel joint operable to telescopically extend and contract the tubing string to compensate for vertical motion of a floating platform. A need has also arisen for such a travel joint that has a reliable locking and unlocking mechanism suitable for tubing string installations in highly deviated wells or wells having restrictions. Further, a need has arisen for such a travel joint that enables stabbing the tubing string into the packer even if the travel joint has become unlocked without the requirement of tripping the travel joint out of the well for resetting or redressing.